Regex problems Java

Question

I am trying to match the following pattern in a string and extract it as a substring.

The pattern always follows

<D-10-helloworld-84>

The 'D' can either be 'D' or 'E' but nothing else. the message in the middle can have any character and each number is always a digit decimal (5 would 05 for example).

I have tried the following:

String text = "sdsas<D-10-helloworld-84>kjvkjv";

Pattern pattern = Pattern.compile("^<[ED]-[0-9]{2}-(.?)-[0-9]{2}>$");
Matcher matcher = pattern.matcher(noiseFrame);
String newText = matcher.group(1);

But not match is being found. What's happening here? Thanks

Community · Accepted Answer · 2020-06-20 09:12:55Z

4

Since your input has some text before/after < and > you need to remove anchors ^ and $ from your regex:

Pattern pattern = Pattern.compile("<[ED]-[0-9]{2}-(.*?)-[0-9]{2}>");

Also it seems you haven't called matchers find() or matches() method which is required before you can call group().

Code:

String text = "sdsas<D-10-helloworld-84>kjvkjv";

Pattern pattern = Pattern.compile("<[ED]-[0-9]{2}-(.*?)-[0-9]{2}>");
Matcher matcher = pattern.matcher(noiseFrame);
if (matcher.find()) {
    String newText = matcher.group(1);
    System.out.println(newText);
}

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Nov 29, 2013 at 15:16

anubhava

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6 Comments

user2863323 Over a year ago

Removed anchors but still no match found.

anubhava Over a year ago

check updated now. It seems you have't called find() or matches() method yet.

user2863323 Over a year ago

in this case all that is happening is newText is being set to "helloworld" without the other parts left and right of it :/

anubhava Over a year ago

It is because you have brackets around inner most part only (.*?) if you want full match you can just use: String newText = matcher.group(0);

user2863323 Over a year ago

The point is not to get the message inside but to get the frame itself all of "<D-10-helloworld-84>" which may appear in a string such as sdsas<D-10-helloworld-84>kjvkjv

|

Paul Vargas · Accepted Answer · 2013-11-29 15:18:05Z

0

Try the next regular expression:

.*<[ED]-[0-9]{2}-([^-]+)-[0-9]{2}>.*

e.g.:

String text = "sdsas<D-10-helloworld-84>kjvkjv";
String newText = text.replaceAll(".*<[ED]-[0-9]{2}-([^-]+)-[0-9]{2}>.*", "$1");

Using a constant:

private static final Pattern REGEX_PATTERN = 
        Pattern.compile(".*<[ED]-[0-9]{2}-([^-]+)-[0-9]{2}>.*");

public static void main(String[] args) {
    String input = "sdsas<D-10-helloworld-84>kjvkjv";

    System.out.println(
        REGEX_PATTERN.matcher(input).matches()
    );  // prints "true"

    System.out.println(
        REGEX_PATTERN.matcher(input).replaceFirst("$1")
    );  // prints "helloworld"
}

answered Nov 29, 2013 at 15:18

Paul Vargas

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